Divorce is the dissolution of a social tie, but it is also possible that attitudes about divorce flow across social ties. To explore how social networks influence divorce and vice versa, we utilize a longitudinal data set from the long-running Framingham Heart Study. We find that divorce can spread between friends, siblings, and coworkers, and there are clusters of divorcees that extend two degrees of separation in the network. We also find that popular people are less likely to get divorced, divorcees have denser social networks, and they are much more likely to remarry other divorcees. Interestingly, we do not find that the presence of children influences the likelihood of divorce, but we do find that each child reduces the susceptibility to being influenced by peers who get divorced. Overall, the results suggest that attending to the health of one’s friends’ marriages serves to support and enhance the durability of one’s own relationship, and that, from a policy perspective, divorce should be understood as a collective phenomenon that extends far beyond those directly affected.

A completely fascinating study published on the Social Science Research Network looked at how likely a marriage was to survive depending on who else in the social network was getting divorced.

The study used data from the famous Framington Heart Study and found that while we tend to think of marriage as a ‘couple thing’ is turns out that even our most intimate bonds are deeply embedded into the social webs we weave.

There’s a profound conservative insight here, I think, about the social consequences of what can seem like purely individual choices. No-fault divorce laws were ushered in, in part, on the understandable theory that they would make it easier to end the small minority of marriages that were miserable shams or abusive hells, without affecting happier, more stable couples. And that theory endures today: In her recent Times op-ed on New York’s decision to join the rest of America in allowing no-fault divorce, for instance, Stephanie Coontz attributes the 1970s surge in marital dissolutions primarily to “pent-up demand for divorces” finally being met by a more accommodating legal system.

Certainly this is part of the truth. (And of course to some extent the legal changes in 1970s America were chasing the cultural changes, rather than the other way around.) But it’s also true that no family is an island, and by facilitating the divorces of unhappy couples we almost certainly changed the way that happier couples — or couples who had considered themselves happy, at least — thought about their marriages, and the possibility of ending them. (It’s telling, in this regard, that the liberalization of divorce laws coincided with an appreciable decline in the percentage of men and women describing their unions as “very happy.”) There’s no escaping peer effects: If your friends or neighbors or relatives get divorced, you’re more likely to get divorced — even if it’s only on the margins — no matter what kind of shape your marriage is in. And inevitably, the ripples keep on spreading, to the next generation and beyond …

No escaping? I have my own anecdotal evidence that ’80s divorces happened “because everyone was doing it.” But I just can’t be persuaded on the strength of one (intriguing) study that a significant percentage of husbands and wifes won’t react to the divorces of others with a greater resolve to stay married. Your read would make a person worry that everyone will succumb, as if to a plague of zombies. Possibly divorce is more like Ebola — very intimate contact with divorce might spike the likelihood of your own divorce, but less intimate contact might more likely scare that likelihood away.

Ross Douthat picks up on a study showing that an individual couple is likelier to get divorced if others in their peer group are getting divorced and comes away with a critique of no-fault divorce laws based off of a very strange conclusion. “If your friends or neighbors or relatives get divorced,” he writes, “you’re more likely to get divorced — even if it’s only on the margins — no matter what kind of shape your marriage is in.”

But that can’t be right: If you’re happy with your partner, if you wake up glad to see their face and go to bed glad to feel their warmth, the fact that someone in your social circle is getting divorced won’t lead you to file papers. I think Ross’s point might be that the availability of divorce changes your perceptions of your marriage because it gives you license to consider other options, but I think we really need to be careful about defining people as “happy” if the possibility of leaving their situation causes them to go through the emotionally and financially grueling process of fleeing. In that scenario, the prevalence of divorce doesn’t change the shape your marriage is in. It changes your willingness to face up to the shape your marriage is in.

Ezra Klein, responding to Douthat, suggests that the causal channel isn’t making people who are happy in their marriages divorce, but leading people to re-evaluate whether they are really happily married, by making it clear that there is an alternative to staying married. “The prevalence of divorce doesn’t change the shape your marriage is in. It changes your willingness to face up to the shape your marriage is in.” (In other words, Klein is suggesting that many people call their marriages “happy” only through the mechanism of adaptive preferences, a.k.a. sour grapes.) Klein has, deservedly, a reputation for being more clueful than his peers, and his response shows a modicum of critical thought, but he is still relying on Ross Douthat to do causal inference, which is a sobering thought.

Both of these gentlemen are assuming that this association between network neighbors’ divorces must be due to some kind of contagion — Douthat is going for some sort of imitation of divorce as such, Klein is looking to more of a social learning process about alternatives and their costs. Both of them ignore the possibility that there is no contagion here at all. Remember homophily: People tend to be friends with those who are like them. I can predict your divorce from your friends’ divorces, because seeing them divorce tells me what kind of people they are, which tells me about what kind of person you are. From the sort of observational data used in this study, it is definitely impossible to say how much of the association is due to homophily and how much to contagion. (The edge-reversal test they employ does not work.) It seems to be impossible to even say whether there is any contagion at all.*

To be clear, I am not castigating columnists for not reading my pre-prints; on balance I’m probably happier that they don’t. But the logical issue of running together influence from friends and inference from the kind of friends you have is clear and well known. (Our contribution was to show that you can’t escape the logic through technical trickery.) One would hope it would have occurred to people to ponder it before calling for over-turning family law, or saying, in effect, “You should stay together, for the sake of your neighbors’ kids”. I also have no problem with McDermott et al. investigating this. It’s a shame that their data is unable to answer the causal questions, but without their hard work in analyzing that data we wouldn’t know there was a phenomenon to be explained.

I hope it’s obvious that I don’t object to people pontificating about whatever they like; certainly I do enough of it. If people can get paying jobs doing it, more power to them. I can even make out a case why ideologically committed opinionators have a role to play in the social life of the mind, like so. It’s a big complicated world full of lots of things which might, conceivably, matter, and it’s hard to keep track of them all, and figure out how one’s principles apply** — it takes time and effort, and those are always in short supply. Communicating ideas takes more time and effort and skill. People who can supply the time, effort and skill to the rest of us, starting from more or less similar principles, thereby do us a service. But only if they are actually trustworthy — actually reasoning and writing in good faith — and know what they are talking about.